In the span of their professional lives a radiologist will read over 10 million images, a dermatologist will analyse 200 000 skin lesions, and a pathologist will review nearly 100 000 specimens. Now imagine a computer doing this work over days, rather than decades, and learning from and refining its diagnostic acumen with each new image. This is the capability that artificial intelligence (AI) will bring to medical care: the potential to interpret clinical data more accurately and more rapidly than medical specialists. Computer-aided diagnostics are nothing new in medicine. What is different now is that with deep learning, a class of machine learning algorithms, the system autonomously learns and improves. But AI will not replace physicians any time soon.